I've built a few custom-framed APM-based quadrotors so far. I don't use the kit power distribution board. I solder my own. On my next quad I would like to implement a power supply configuration I often use on my land-based robots, which is to have one power connection going to the motors and another power connection going directly to the Arduino Mega board (and then on to the other electronics through the 5V regulator of the Arduino Mega). Here is the idea:
There would be one 11.1v LIPO as usual. I would split the cable so that one side goes to the four ESCs (and onward to the motors). The other side would go directly to the "VIN: +6V-12v" pins on the APM board. I wouldn't use the BEC at all. Only the signal wires of the ESCs would be connected to the ESC rail. Both power sides would be connectable and un-connectable. This way I could power the APM/electronics without powering the ESCs/motors.
Would this approach work OK on the ArduPilot Mega?
If I had the "electronics" side connected (but not the motors), I assume it would power the APM (and also the GPS and Sonar) just the way it does now. Would it also power the Radio Receiver through the Receiver rail as usual?
Does anyone see any problems with the approach I'm describing? Am I missing something?
Replies
Hi everyone, I really want to know If I wanted to supply power to my APM v1.4 through VIN pin by 7.2v adaptor then what should be the max current (amp) of the adaptor ?
This sounds like it will work fine.
There is a solder jumper near those VIN pins that completely disconnects the 5V (middle) pins on the servo rail from the rest of the board. You'll want to leave it connected to power the receiver from the on-board LM317 regulator, but just make sure you don't ever connect an ESC 5V pin by mistake.
Regulating 11.1V (or really up to 12.6 fully charged) down to 5V, you'll be burning off a bit of power in the LM317. It's nothing for a quad-sized lipo, but you might check your 5V current draw from the APM and all the peripherals, and do a quick calculation to see how much power is dissipated in the regulator.
A friend of mine uses a separate 5V switching BEC to power all his electronics. There's a smallish (11g) one made by Castle Creations that I've used in other projects.